Our previous studies have discovered new stress protein families, i.e. the hsp110 and grpl70 families, and we have characterized their molecular chaperone functions. We have shown that both hsp110 and grpl70 are highly efficient in binding to and stabilizing substrate proteins during heat shock. In the present application we use this new knowledge to formulate novel cancer vaccines by replacing the reporter proteins used in our earlier studies with a major tumor protein antigen, her-2/neu. Chaperone complexes between hsp 110 or grp 170 and the intracellular or extracellular domains of her-2/neu are formed by heat shock. These chaperone complexes are then tested for vaccine activity. Ovalbumin, a well-characterized model antigen, is then used in complex with hsp110 or grpl70 for mechanistic studies to understand how vaccine activity is obtained. In Aim 1 we will determine whether the natural chaperone complexes between the intracellular or extracellular domains of her-2/neu and hsp110 or grp 170 have anti-tumor activity in mice. This will utilize a spontaneous her-2-neu expressing mouse transgenic model, which closely mimics the human disease. In Aim 2, we will investigate the mechanisms by which these vaccines function using a well characterized model system, the Ovalbumin system. This aim will investigate receptor binding of hspll0- and grpl70- Ova complexes, their uptake and processing in dendritic cells. Aim 3 will determine whether hsp110 and grp 170 can function to mature dendritic cells necessary for antigen presentation and determine if this occurs via an NF-kB pathway. Finally, Aim 4 will determine the functional domains of hsp110 and grpl70 involved in their immunological activities defined in the first three aims. These studies will define the mechanisms of action of targeted, natural chaperone complexes of recombinant heat shock proteins with a major protein antigen as cancer vaccines. The characterization of these hsp-protein vaccines and how they function can be expected to define new strategies for the use of hsp-vaccine therapy and to have immediate clinical application.